Your heart and
its voice

Where exactly do heart
sounds come from and
how are they made?

Heart anatomy and
blood flow


Heart rhythm


Heart sounds

Your heart cycle is split into 2 phases: Systole and Diastole, defined by the pressure in your heart.

Systole (Contraction Phase):
During systole, the contraction of the heart occurs and blood is pumped from the ventricles into the body and lungs.

Diastole (Relaxation Phase):
The Diastole phase allow a pause for your heart : this gives time for the atria and ventricles to fill with blood again. During Diastole, the blood pressure is a lot lower than during Systole leading to quieter heart sounds.

When the blood comes in, your heart valves close and make the first heart sound: Lub.
The sound is made of two parts that happens in a fraction of time after one another.

Part 1: Mitral Valve (Left)
Your blood rushes into your left ventricle, it fills up and pushes the valve closed behind it. This causes the blood rushing in from the atrium to crash into the valve creating a heart sound.

Part 2: Tricuspid Valve (Right)
The same happens for your valve on the right side with blood crashing into the tricuspid valve creating the second part of the first heart sound.

When the heart squeezes to push blood throughout the body, the closing of the second valves makes the second heart sound: Dub.
This is also made of made up of two parts:

Part 1: Aortic valve (Left side)
When the pressure in the left ventricle finally builds up enough it pushes open the valve to your aorta and blood flows. After the blood is in the aorta, it will fall towards the ventricle pushing the valve closed so blood does not fall back into your heart. The blood hitting the valve sends vibrations causing a heart sound.

Part 2: Pulmonary valve (Right side)
The same thing occurs on your right side with the blood closing the pulmonary valve causing the second part of the second heart sound.

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A research project led by King's College London and the University of Maastricht.
App and website designed by Cellule Studio 2020.
Funded by the Wellcome Trust and by the European Union’s Horizon 2020 (g.a. 764738).
Supported by the British Heart Foundation and Evelina Children's Heart Organisation.